1. Field of Invention
The invention relates generally to the field of electronics manufacturing and, more specifically, to a method and apparatus for determining optimal positions for making alignment holes in the packaging of a optical diode device, such as a laser diode or photo detecting diode.
2. Description of Related Art
Optical diode devices are semiconductor devices that are commonly used in many applications. Transmitting devices output light in response to an electrical excitation. The devices output incoherent light when the excitation is below a lasing threshold. In this case, the devices operate as light-emitting diodes due to spontaneous emission. Once the lasing threshold is reached, the devices output laser light due to stimulated emission, which can be in any spectrum, whether visible or not. Moreover, photo detecting diodes, such as p-i-n diodes, receive a light input and produce a corresponding electrical output. The photo detecting diodes, also known as pixels, measure photon flux at different spatial points.
Transmitting and receiving optical devices are therefore very useful in transmitters and receivers for fiber optic communications and many other applications. Moreover, during manufacture, 1-D and 2-D arrays of the optical devices may be produced to increase their effectiveness.
The optical device must be carefully aligned when it is installed in the end use device, such as a customer transceiver assembly. Typically, the optical device is carried in packaging in which alignment structures such as through holes are made for mating with, e.g., pins, in the end use device. The alignment structures are positioned in a specific orientation with respect to the optical device. For example, the alignment structures may be positioned so that collimating optics for an optical fiber are centered over the optical device.
However, accurately making the alignment structures is problematic. For example, making précising, e.g., alignment, holes to align optical diode devices is currently accomplished by manually aligning to each device, or to portions of a diode array. This type of alignment is very subjective and operator intensive. The quality of the hole positioning is not determined until the module is completed and a coupling test is done. If the device does not couple well enough, then it is rejected. After précising holes are drilled, a separate hole alignment measurement is made. The correlation between the alignment measurement and the coupling quality has never been made. The correlation between the two measurements has many variables and interactions such as axis skew in more than the single-plane hole alignment measurement. In the past, the resulting yield was accepted. For example, parts were rejected from processing for hole alignment errors greater than, e.g., +/−10 microns, or a coupling loss greater than a customer specification, before assembly into the transceiver module.